Up to now, as everybody knows, LTE is deployed in licensed carriers for operation. However, with the evolution of LTE, in the second half year of 2013, some companies (e.g., America Qualcomm Incorporated) put forward a suggestion of studying a subject of deploying LTE on unlicensed carriers. However, up to now, the suggestion has not been accepted by LTE and no project has been set up.
A reason, provided by Qualcomm Incorporated, for setting up a project is mainly that, with the quick increase of data service, in the near future, licensed spectrums cannot bear such huge data volume. Therefore, it is suggested to deploy LTE in unlicensed spectrums, so as to share data flow in licensed carriers through the unlicensed spectrums.
Moreover, the unlicensed spectrums also have many advantages. For example, the unlicensed spectrums have the following features and advantages:
1. free/low expense (the unlicensed spectrums do not need to be purchased and the spectrum resources are zero-cost);
2. low admission requirement and low cost (individuals and enterprises may participate in deployment and devices of device providers may be randomly selected);
3. resource sharing (when a plurality of different systems operate therein or different operators of the same system operate therein, some resource sharing modes may be considered to improve spectrum efficiency);
4. numerous radio access technologies (it is difficult to realize collaboration across different communication standards and network topologies are diversified);
5. numerous radio access websites (the number of users is great, the collaboration difficulty is great and the centralized management overhead is great);
6. numerous applications (according to information, multiple services such as Machine to Machine (M2) and Vehicle to Vehicle (V2V) are mentioned to be capable of operating therein).
The above-mentioned basic features decide that the unlicensed spectrums may be an important evolution direction of radio communication systems, but many problems exist at the same time. For example, various systems exist in the unlicensed spectrums, it is difficult to realize coordination and the interference is serious.
If an LTE system operates on an unlicensed carrier, there is a problem how an LTE base station informs other nearby base stations when the LTE base station seizes an unlicensed carrier resource.
Aiming at the problem of how to enable base stations to mutually inform about an occupation situation of the unlicensed carrier, up to now no effective solution has already been put forward.